Catalyst for the production of acrylonitrile

ABSTRACT

IN THE PRODUCTION OF ACRYLONITRILE BY A VAPOR PHASE REACTION OF PROPYLENE, AMMONIA AND OXYGEN AT AN ELEVATED TEMPERATURE, A PROCESS WHICH COMPRISES CONTACTING PROPYLENE, AMMONIA AND OXYGEN WITH A CATALYST COMPOSITION COMPRISING A CATALYST SYSTEM OF THE FORMULA:   TLAPBMOCFEDBIEMNFXGOH   WHEREIN X REPRESENTS ONE OR MORE OF THE METALS, NI, MG AND CO AND A, B, C, D, E, F, G AND H REPRESENT, RESPECTIVELY, THE RELATIVE NUMBER OF ATOMS OF EACH COMPONENT, PROVIDED THAT, WHEN C IS 12, A IS 2 OR LESS, BUT NOT 0, B IS 0 5, E IS 0.1 TO 5, F IS NOT MORE THAN 15 BUT NOT 0, G IS 0 TO 15, F+G IS 2 TO 15, AND H IS DECIDED OR DETERMINED DEPENDING ON THE NUMBER OF THE OTHER ATOMS AND IS USUALLY FROM 38.3 TO 81.5.

United States Patent US. Cl. 252-437 5 Claims ABSTRACT OF THE DISCLOSUREIn the production of acrylonitrile by a vapor phase reaction ofpropylene, ammonia and oxygen at an elevated temperature, a processwhich comprises contacting propylene, ammonia and oxygen with a catalystcomposition comprising a catalyst system of the formula:

wherein X represents one or more of the metals, Ni, Mg and Co and a, b,c, d, e, f, g and h represent, respectively, the relative number ofatoms of each component; provided that, when c is 12, a is 2 or less,but not 0, b is 5; e is 0.1 to 5; f is not more than 15 but not 0; g is0 to 15; f+g is 2 to 15; and h is decided or determined depending on thenumber of the other atoms and is usually from 38.3 to 81.5.

The present invention relates to a process for producing acrylonitrile.More particularly, it relates to a process for selective production ofacrylonitrile by the vapor phase reaction of propylene, ammonia andoxygen in the presence of a specific catalyst system.

For the production of acrylonitrile by ammoxidation of propylene, therehave been proposed a variety of catalyst systems. Some examples of thesesystems are as follows: a catalyst system comprising bismuth, tin orantimony salt of molybdic acid or phosphomolybdic acid, or bismuthphosphowolframate (Japanese patent publication No. 5,870/ 1961); acatalyst system comprising the oxides of bolybdenum, phosphorus, bismuthand iron (Japanese patent publication No. 17,967/19'63); a catalystsystem comprising the oxides of copper and antimony (Japanese patentpublication No. 14,093/ 1966); a catalyst system comprising the oxidesof bismuth and tungsten (Japanese patent publication No. 27,402/1968); acatalyst system comprising the oxides of uranium and antimony (Japanesepatent publication No. 2.4,367/1965), etc. However, some drawback areseen in these known catalyst systems.

One of the drawbacks is the production of acrylonitrile in a relativelylow selectivity. Thus, there are by-produced carbon monoxide, carbondioxide, acrolein, acetaldehyde, acetonitrile, hydrogen cyanide and thelike in large amounts, which reduce the yield of acrylonitrile.Moreover, the production of these by-products results not only in theloss of the starting materials, but also in the difiicult recovery ofthe desired acrylonitrile.

Another drawback is the low yield of acrylonitrile in each pass ofpropylene feed. This is probably due to the low conversion of propyleneor, even if the conversion of propylene may be high, the low selectivityto acrylonitrile.

-A further drawback of these known systems is the production ofexcessively oxidized by-products such as carbon monoxide and carbondioxide, which makes the control of heat diflicult. The side reactionsare more exothermic than the main reaction, and a larger amount of adiluent is required to control the heat generating therefrom.

3,741,910 Patented June 26, 1973 ice As a result of extensive studies,it has been found in accordance with this invention, that the use of aspecific catalyst system comprising thallium in the ammoxidation ofpropylene will afford acrylonitrile with a high selectivity in anexcellent yield per each pass. It has also been found that the use ofthis system suppresses considerably the formation of undesirableby-products, especially carbon monoxide and carbon dioxide, and makes itpossible to carry out the reaction at a relatively low temperature. Thepresent invention is based on these findings.

According to the present invention, the vapor phase reaction ofpropylene, ammonia and oxygen is carried out in the presence of acatalyst system corresponding to the formula: 'I'l P Mo -Fe Bi Mn X O'wherein X represents one or more metals selected from the groupconsisting of Ni, Mg and Co, and a, b, c, d, e, f, g and h represent,respectively, the number of atoms of each component; provided that, when0 is 12, a is 2 or less (preferably 0.01 to 1.0) but not 0; b is 0.5(preferably 0.01 to 3.0); d is 0.1 to 5; e is 0.1 to 5 (preferably 0.5to 3.0); f is not more than 15 (preferably not more than 12) but not 0;g is 0 to 15 (preferably 0 to 12); f+g is 2 to 15 (preferably 2 to 12);and h is decided or determined depending on the number of the otheratoms and is usually from 38.3 to 81.5 (preferably 38.9 to 69:0).

The starting materials in the ammoxidation of this invention arepropylene, ammonia and oxygen. The propylene is not necessarily requiredto be highly pure and may contain, for instance, some amounts of lowmolecular weight saturated hydrocarbons such as propane. As the oxygensource, there may be used pure oxygen gas, air enhanced or not in theoxygen concentration or any other free oxygen-containing gas. From theeconomical viewpoint, the use of air is preferred. In order to increasethe selectivity to acrylonitrile, steam may be introduced into thereaction system, but this introduction is not necessarily required. Ifdesired, an approximate inert gas such as nitrogen, carbon dioxide, orargon may be used as a diluent. I

For preparation of the catalyst system, there may be employed metallicthallium and thallium compounds (e.g. thallium nitrate, thalliumcarbonate, and thallium chloride), molybdenum compounds (e.g. ammoniummolybdate, molybdenum oxide, molybdic acid and phosphomolybdic acid),phosphorus compounds (e.g. phosphoric acid, ammonium phosphate, andphosphorus pentoxide), iron compounds (e.g. ferric nitrate, and ferricchloride), bismuth compounds (e.g. bismuth nitrate, bismuth chloride andbismuth oxide), magnesium compounds (e.g. magnesium nitrate andmagnesium chloride), cobalt compounds (e.g. cobalt nitrate and cobaltchloride), nickel compounds (e.g. nickel nitrate, and nickel chloride)and manganese compounds (e.g. manganese nitrate and manganese chloride).

The catalyst system may be used as such but it is advantageouslyincorporated with a suitable carrier (e.g. silica, alumina, siliconcarbide, titanium oxide). The amount of the carrier is varied with itskind and may he usually less than by weight, preferably from 5 to 90% byweight, of the catalyst composition. The catalyst composition isnormally formed in tablets or granules on use.

The preparation of the mixed oxide catalyst composition may be executedby a per se conventional procedure. For instance, a thallium salt, aniron salt, a bismuth salt, a phosphorus compound, a manganese salt andone or more of a magnesium salt, a cobalt salt and a nickel salt areadded to an aqueous solution of a molybdate such as ammonium molybdate;the resulting slurry is admixed with a carrier material and evaporatedto dryness; and the resultant cake is calcined at an elevatedtemperature in atmosphere and, after cooling, crushed and shaped intopellets or granules.

The production of acrylonitrile using the catalyst composition of theinvention may be effected by a fluidized bed process or a fixed bedprocess. The reaction temperature is associated with the kind of thecatalyst composition and usually from about 300 to about 520 0.,preferably from about 350 to about 480 C. The reaction is usuallycarried out at a nearly atmospheric pressure (preferably about 0.7 toabout 5 atm.). The molar ratio of the starting materials may bepropylenezammoniamxygen: 1.0: 0.7-2.5

(favorably 1.0-2.0) :1.05.0 (favorably 1.5-3.5). When steam is used, itmay be usually not more than about 18 mol, favorably from about 1 toabout mol per 1 mol of propylene. The space velocity is ordinarily fromabout 50 to about 2000 hr. preferably from about 100 to about 1000 hr.-'

By the use of the catalyst system of the present invention, the desiredacrylonitrile can be produced in a high selectivity and an excellentyield per each pass with little by-production of carbon monoxide andcarbon dioxide. In addition, the life of the catalytic activity issufficiently and satisfactorily long and the thallium in the catalystcomposition is never volatilized during the reaction.

A number of preferred embodiments of the present invention are shown inthe following examples.

IEXAMPLE l (A) Thallium nitrate (1.33 g.) ferric nitrate (10.10 g.),manganese nitrate (7.18 g.), magnesium nitrate (6.41 g.), cobalt nitrate(7.28 g.) and nickel nitrate (39.99 g.) are dissolved in distilled water(300 ml.) and bismuth nitrate (12.13 g.) is dissolved in dilute nitricacid (6% by weight; 25 ml.). These solutions are combined together. Theresultant mixture is added to a solution of ammonium molybdate (52.98g.) in dilute aqueous ammonia (3.5% by weight; 300 ml.) containingphosphoric acid (85% by weight; 0.23 g.). To the resultant slurrydispersion, silica sol (SiO 20% by Weight; 100 ml.) is added, and themixture is evaporated to dryness until the generation of nitrogendioxide is ceased. The residue is calcined at 300 C. for 3 hours (firstcalcination), cooled and crushed. The obtained powder is tableted andcalcined at 550 C. for 6 hours (2nd calcination) to give a catalystcomposition, of which the active components correspond to the formula:Ti P Mo Fe Bi Mn Mg Co Ni 0 (wherein the carrier is omitted).

(B) In a glass-made reaction tube of 10 mm. in inner diameter, theabove-obtained catalyst composition 6 ml.) is charged and heated up to410 C. Then, a gaseous mixture of propylene, ammonia, oxygen, steam andnitrogen (1.0:1.2:2.8:9.0:6.8 in molar ratio) is introduced into thereaction tube at a space velocity of 550 III-"1, whereby acrylonitrileis produced.

The conversion of propylene is 100% and the selectivities toacrylonitrile, carbon monoxide and carbon dioxide are respectively 80%,7.0% and 6.1%, when calculated according to the following equations:

Conversion of propylene (percent) Reacted propylene (mol) X 100 Feedpropylene (mol) Selectivity (percent) Weight of carbon atoms in productWeight of carbon atoms in reacted propylene EXAMPLE 2 4 spond t0 theformula: Tlo 2P0 3MO 2FC BI1MII4NI4 5O4 is prepared.

As in Example 1, a gaseous mixture of propylene, ammonia, oxygen, steamand nitrogen (1.0:1.1:2.9:8.7:6.3 in molar ratio) is contacted with theabove-obtained catalyst composition (6 ml.) at 440 C. at a spacevelocity of 540 hrr whereby acrylonitrile is produced. The conversion ofpropylene is 96% and the selectivities to acrylonitrile, carbon monoxideand carbon dioxide are, respectively 88%, 2.0% and 2.2%.

EXAMPLE 3 In the same manner as in Example 1, except that cobalt nitrateand magnesium nitrate are not used, and the amount of nickel nitrate ischanged to 54.53 g., a catalyst composition of which the activecomponents corresponds to the formula: TI P ogMomFe Bi MnlNiq504; ISPIC- pared.

As in Example 1, a gaseous mixture of propylene, ammonia, oxygen, steamand nitrogen (1.0: l.l:3.0:8.6:6.6 in molar ratio) is contacted with theabove-obtained catalyst composition (6 ml.) at 410 C. at a spacevelocity of 550 hr.- whereby acrylonitrile is produced. The conversionof propylene is 96% and the selectivities to acrylonitrile, carbonmonoxide and carbon dioxide are, respectively 82%, 3.2% and 5.0%.

EXAMPLE 4 In the same manner as in Example 1, except that nickel nitrateand cobalt nitrate are not used, and the amounts of manganese nitrateand magnesium nitrate are changed, respectively to 3.59 g. and 54.49 g.,a catalyst composition of which the active components correspond to theformu 1a! n.2 0.os 12 1 1 oj so mn is P p As in Example 1, a gaseousmixture of propylene, ammonia, oxygen, steam and nitrogen(1.0:1.2:2.9':4.8:6.9 in molar ratio) is contacted with theabove-obtained catalyst composition (6 ml.) at 430 C. at a spacevelocity of 405 hr.- whereby acrylonitrile is produced. The conversionof propylene is 90% and the selectivities to acrylonitrile, carbonmonoxide and carbon dioxide are respectively 79%, 4.8% and 4.5%.

EXAMPLE 5 In the same manner as in Example 1, except that magnesiumnitrate and nickel nitrate are not used, and the amounts of manganesenitrate and cobalt nitrate are changed, respectively, to 14.35 g. and43.66 g., a catalyst composition of which the active componentscorrespond to the formula: Ti P Mo Fe Bi Mn Co O is prepared.

As in Example 1, a gaseous mixture of propylene, ammonia, oxygen, steamand nitrogen (l.0:1.2:3.0:8.9:6.8 in molar ratio) is contacted with theabove-obtained cata lyst composition (6 ml.) at 390 C. at a spacevelocity of 540 hrf whereby acrylonitrile is produced. The conversion ofpropylene is 99.6% and the selectivities to acrylonitrile, carbonmonoxide and carbon dioxide are, respectively 84%, 5.6% and 5.5%.

EXAMPLE 6 In the same manner as in Example 1, except that cobalt nitrateis not used, and the amounts of manganese nitrate and magnesium nitrateare changed, respectively to 3.59 g. and 16.03 g., a catalyst of whichthe active components correspond to the formula:

az o.os la i i o.s as s.5 4s.o

is prepared.

As in Example 1, a gaseous mixture of propylene, ammonia, oxygen, steamand nitrogen (1.0:1.2:3.0:8.8:6.6 in molar ratio) is contacted with theabove obtained catalyst composition (6 ml.) at 390 C. at a spacevelocity of 540 hr. whereby acrylonitrile is produced. The conversion ofpropylene is 96% and the selectivities to acrylonitrile, carbon monoxideand carbon dioxide are, respectively 87%, 1.8% and 2.9%.

EXAMPLE 7 In the same manner as in Example 1, except that magnesiumnitrate is not used, and the amounts of manganese nitrate and cobaltnitrate are changed, respectively to 3.59 g. and 18.19 g., a catalystcomposition of which the active components correspond to the formula:

As in Example 1, a gaseous mixture of propylene, ammonia, oxygen, steamand nitrogen (1.0: 1.1:2.8:8.7:6.4 in molar ratio) is contacted with theabove-obtained catalyst composition (6 ml.) at 410 C. at a spacevelocity of 410 hr. whereby acrylonitrile is produced. The conversion ofpropylene is 100% and the selectivities to acrylonitrile, carbonmonoxide and carbon dioxide are, respectively, 82%, 3.8% and 5.5%.

REFERENCE EXAMPLE In the same manner as in Example 1, except thatthallium nitrate is not used, a catalyst composition of which the activecomponents correspond to the formula: Po 03MO1 F Bi1MD Mg CO1Ni55047 isprepared.

As in Example 1, a gaseous mixture of propylene, ammonia, oxygen, steamand nitrogen (1.0:1.2:2.8:8.9:6.8 in molar ratio) is contacted with theabove-obtained catalyst composition (6 m1.) at 410 C. at a spacevelocity of 550 hrr whereby acrylom'trile is produced. The conversion ofpropylene is 99.5% and the selectivities to acrylonitrile, carbonmonoxide and carbon dioxide are respectively 53%, 13.1% and 10.6%.

What is claimed is:

1. A catalyst composition comprising a catalyst system 6 of the formula:T1 P Mo Fe Bi Mn X O wherein X is Ni, Mg, Co or mixtures thereof and a,b, c, d, e, f, g, and 11 represent, respectively, the number of atomsand c is 12, a is 2 or less, but not 0; b is 0 to 5; d is 0.1 to 5; e is0.1 to 5; f is not more than 15 but not 0; g is 0 to 15; f-I-g is 2 to15; and h is from 38.3 to 81.5.

2. A catalyst composition according to claim 1, wherein a is 0.01 to1.0; b is 0.01 to 3.0; d is 0.1 to 5; e is 0.5 to 3.0; f is not morethan 12, but not 0; g is 0 to 12; f+g is 2 to 12; and h is from 38.9 to69.0.

3. A catalyst composition according to claim 1, wherein said catalystcomposition is incorporated with a carrier selected from the groupconsisting of silica, alumina, silicon carbide and titanium oxide.

4. A catalyst composition according to claim 3 wherein the amount of thecarrier is less than by weight, of said catalyst composition.

5. A catalyst composition according to claim 3, wherein the amount ofthe carrier is from 5 to 90% by weight of said catalyst composition.

References Cited UNITED STATES PATENTS 2,995,528 8/1961 Dowden et al252464 3,102,147 8/1963 Johnson 252437 X 3,157,688 11/1964 Arnold et a1252437 X 3,254,110 5/1966 Sennewald et al. 252437 X 3,576,764 4/ 1971Yamaguchi et al. 252437 PATRICK P. GAVIN, Primary Examiner US. Cl. X.R.

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION P t a 741 910Dated June 26. 1973 Inventor(s) Shiraishi, et a1 It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as" shown below:

Column 1,

lines 25' and 26, change bis 05; e" to -b is 0 to 5; d m0. 1 to 5;e-1ine 44, change "bolybdenum" to --mo1ybdenu'm'--. Column 2, v line 19,change "0. 5" to 0 to 5-. Column 3,

line 48, change "Ti" to --T1--;

line 51, before "6", insert Column 4,

line 1, change "Ti" to -T1-;

line 17, change "Ti" to -T1--; 1 line 34, change "Ti" to --T1-. Column5,

line 10,-" change "T-" to -T1-.

Co1umn6, line 1, change "T1 to -T1 'Signed and sealed. this 16th day ofJuly 1971+.

(SEAL) Attest:

McCOY M. GIBSON, JR. c. MARSHALL DANN Attesting Officer Commisslone'r ofPatents Form Po-wso (10-69) o: ooanmoo O In. ovuuupyymnuc amt; nu o-au-gg V

